This article explores a cultural history of peppercorn and its famous characterization as a “numbing spice.” It investigates how the quality of “numbing spice” extended from East Asian cosmologies that engaged with peppercorn, also known as mountain pepper or sanshō 山椒 , as a medical, literary, and culinary object. Medieval and early modern encyclopedias in China described how the plant's vivid colors reflected cosmological relationships that promised better health and eternal youth. The plant's desirability represented what I call “numbing aesthetics,” in that its taste was directly tied to its appearance and utility. When burned, boiled, or crushed, forms of peppercorn could treat hemorrhages, hair loss, swollen scrotums, and toothaches. Beautiful peppers were more effective; ugly peppers were less effective. These many types of plants had many kinds of names with origin stories that derived from young girls, young couples, pigs, and frogs. As a social metaphor, pepper dust became a popular metaphor for describing confined concubines. This article later argues that these qualities fell away when biologists attempted to reduce the plant into its active molecular components in the twentieth century. Tokyo-based chemists imperfectly distilled numbing juices from the pepper's bark and fruit to define numbness as a single unit of flavor, even when numbness was not a classical kind of flavor and more closely resembled tingling vibrations. But by becoming a quasi-category of flavor, the molecularization of peppercorn would diminish its long history of cosmological associations that were gendered, practiced, and otherworldly.